Transfer control to another fiber, resuming it from where it last stopped or starting it if it was not resumed before. The calling fiber will be suspended much like in a call to Fiber.yield.
The fiber which receives the transfer call treats it much like a resume call. Arguments passed to transfer are treated like those passed to resume.
The two style of control passing to and from fiber (one is resume and Fiber::yield, another is transfer to and from fiber) can’t be freely mixed.
If the Fiber’s lifecycle had started with transfer, it will never be able to yield or be resumed control passing, only finish or transfer back. (It still can resume other fibers that are allowed to be resumed.)
If the Fiber’s lifecycle had started with resume, it can yield or transfer to another Fiber, but can receive control back only the way compatible with the way it was given away: if it had transferred, it only can be transferred back, and if it had yielded, it only can be resumed back. After that, it again can transfer or yield.
If those rules are broken FiberError is raised.
For an individual Fiber design, yield/resume is easier to use (the Fiber just gives away control, it doesn’t need to think about who the control is given to), while transfer is more flexible for complex cases, allowing to build arbitrary graphs of Fibers dependent on each other.
Example:
manager = nil # For local var to be visible inside worker block # This fiber would be started with transfer # It can't yield, and can't be resumed worker = Fiber.new { |work| puts "Worker: starts" puts "Worker: Performed #{work.inspect}, transferring back" # Fiber.yield # this would raise FiberError: attempt to yield on a not resumed fiber # manager.resume # this would raise FiberError: attempt to resume a resumed fiber (double resume) manager.transfer(work.capitalize) } # This fiber would be started with resume # It can yield or transfer, and can be transferred # back or resumed manager = Fiber.new { puts "Manager: starts" puts "Manager: transferring 'something' to worker" result = worker.transfer('something') puts "Manager: worker returned #{result.inspect}" # worker.resume # this would raise FiberError: attempt to resume a transferring fiber Fiber.yield # this is OK, the fiber transferred from and to, now it can yield puts "Manager: finished" } puts "Starting the manager" manager.resume puts "Resuming the manager" # manager.transfer # this would raise FiberError: attempt to transfer to a yielding fiber manager.resume
produces
Starting the manager Manager: starts Manager: transferring 'something' to worker Worker: starts Worker: Performed "something", transferring back Manager: worker returned "Something" Resuming the manager Manager: finished
Returns the Fiber scheduler, that was last set for the current thread with Fiber.set_scheduler. Returns nil if no scheduler is set (which is the default), and non-blocking fibers’ behavior is the same as blocking. (see “Non-blocking fibers” section in class docs for details about the scheduler concept).
Returns the dirpath string that was used to create self (or nil if created by method Dir.for_fd):
Dir.new('example').path # => "example"
Sets the position in self and returns self. The value of position should have been returned from an earlier call to tell; if not, the return values from subsequent calls to read are unspecified.
See Dir As Stream-Like.
Examples:
dir = Dir.new('example') dir.pos # => 0 dir.seek(3) # => #<Dir:example> dir.pos # => 3 dir.seek(30) # => #<Dir:example> dir.pos # => 5
Closes the stream in self, if it is open, and returns nil; ignored if self is already closed:
dir = Dir.new('example') dir.read # => "." dir.close # => nil dir.close # => nil dir.read # Raises IOError.
Returns whether dirpath specifies an empty directory:
dirpath = '/tmp/foo' Dir.mkdir(dirpath) Dir.empty?(dirpath) # => true Dir.empty?('/example') # => false Dir.empty?('/example/main.rb') # => false
Raises an exception if dirpath does not specify a directory or file in the underlying file system.
Creates a new Dir object dir for the directory at dirpath.
With no block, the method equivalent to Dir.new(dirpath, encoding):
Dir.open('.') # => #<Dir:.>
With a block given, the block is called with the created dir; on block exit dir is closed and the block’s value is returned:
Dir.open('.') {|dir| dir.inspect } # => "#<Dir:.>"
The value given with optional keyword argument encoding specifies the encoding for the directory entry names; if nil (the default), the file system’s encoding is used:
Dir.open('.').read.encoding # => #<Encoding:UTF-8> Dir.open('.', encoding: 'US-ASCII').read.encoding # => #<Encoding:US-ASCII>
Returns the last access time for the named file as a Time object.
file_name can be an IO object.
File.atime("testfile") #=> Wed Apr 09 08:51:48 CDT 2003
Returns the modification time for the named file as a Time object.
file_name can be an IO object.
File.mtime("testfile") #=> Tue Apr 08 12:58:04 CDT 2003
Returns the change time for the named file (the time at which directory information about the file was changed, not the file itself).
file_name can be an IO object.
Note that on Windows (NTFS), returns creation time (birth time).
File.ctime("testfile") #=> Wed Apr 09 08:53:13 CDT 2003
Returns the birth time for the named file.
file_name can be an IO object.
File.birthtime("testfile") #=> Wed Apr 09 08:53:13 CDT 2003
If the platform doesn’t have birthtime, raises NotImplementedError.
Sets the access and modification times of each named file to the first two arguments. If a file is a symlink, this method acts upon its referent rather than the link itself; for the inverse behavior see File.lutime. Returns the number of file names in the argument list.
Sets the access and modification times of each named file to the first two arguments. If a file is a symlink, this method acts upon the link itself as opposed to its referent; for the inverse behavior, see File.utime. Returns the number of file names in the argument list.
Returns the real (absolute) pathname of pathname in the actual filesystem not containing symlinks or useless dots.
If dir_string is given, it is used as a base directory for interpreting relative pathname instead of the current directory.
All components of the pathname must exist when this method is called.
Returns the real (absolute) pathname of pathname in the actual filesystem. The real pathname doesn’t contain symlinks or useless dots.
If dir_string is given, it is used as a base directory for interpreting relative pathname instead of the current directory.
The last component of the real pathname can be nonexistent.
Returns the last component of the filename given in file_name (after first stripping trailing separators), which can be formed using both File::SEPARATOR and File::ALT_SEPARATOR as the separator when File::ALT_SEPARATOR is not nil. If suffix is given and present at the end of file_name, it is removed. If suffix is “.*”, any extension will be removed.
File.basename("/home/gumby/work/ruby.rb") #=> "ruby.rb" File.basename("/home/gumby/work/ruby.rb", ".rb") #=> "ruby" File.basename("/home/gumby/work/ruby.rb", ".*") #=> "ruby"
Returns the string representation of the path
File.path(File::NULL) #=> "/dev/null" File.path(Pathname.new("/tmp")) #=> "/tmp"
Returns the last access time (a Time object) for file, or epoch if file has not been accessed.
File.new("testfile").atime #=> Wed Dec 31 18:00:00 CST 1969
Returns the modification time for file.
File.new("testfile").mtime #=> Wed Apr 09 08:53:14 CDT 2003
Returns the change time for file (that is, the time directory information about the file was changed, not the file itself).
Note that on Windows (NTFS), returns creation time (birth time).
File.new("testfile").ctime #=> Wed Apr 09 08:53:14 CDT 2003
Returns the birth time for file.
File.new("testfile").birthtime #=> Wed Apr 09 08:53:14 CDT 2003
If the platform doesn’t have birthtime, raises NotImplementedError.
Returns true if the named file exists and has a zero size.
file_name can be an IO object.
Returns true if the named file exists and has a zero size.
file_name can be an IO object.
Returns true if filepath points to a character device, false otherwise.
File.chardev?($stdin) # => true File.chardev?('t.txt') # => false